New Delhi: Drinkers of hot tea do not face an increased risk of esophageal cancer, but those who also consume excessive alcohol and smoke have five times higher risk than people who have none of the three habits.

Chinese scientists today released the findings of a large study that has detected what they say is a “noticeable increase” in the risk of esophageal cancer associated with a combination of hot tea drinking, excessive alcohol consumption and tobacco smoking.

Those who drank “burning-hot tea” and consumed 15 grams or more of alcohol daily had the greatest risk of esophageal cancer, a five-fold increase over people who did neither, nor smoked, and a two-fold increase over smokers who also drank burning-hot tea.

Public health researcher Jun Lv and her colleagues in Beijing tracked 456,155 persons between the ages of 30 and 79 years from 10 regions across China between 2004 and 2008. They questioned the study participants about their tea, alcohol and smokng patterns and followed them up for incidence of esophageal cancer up to 2015.

The study comes against the backdrop of earlier research nine years ago that had hinted that hot tea may be an additional risk factor for esophageal cancer, a type of cancer that has poor survival rates worldwide and has long been linked to alcohol and smoking.

A 2009 study from northern Iran’s Golestan province which has among the world’s highest rates of esophageal cancer had found that drinking hot tea –70 degrees C or higher – was associated with an eight-fold increased risk than drinking lukewarm tea – below 65 degrees C.

Now, the Chinese researchers have found that the association between the hot tea drinking and esophageal cancer risk is “dependent on alcohol and tobacco consumption” habits.  

“In the absence of both excessive alcohol consumption and smoking, daily hot tea drinking was not associated with esophageal cancer risk, regardless of the tea temperature and other consumption measures,” the Chinese team said, describing their findings in the US research journal, Annals of Internal Medicine.

The scientists say this “synergistic effects” of hot tea drinking, excessive alcohol consumption and smoking on the risk of the cancer is “biologically plausible,” because earlier research has shown that thermal injury may damage the membrane called epithelium and augment the risk of damage from alcohol and smoke.

The Chinese study is being viewed as significant as it is among the world’s largest studies on hot beverages and the esophageal cancer risk. Some surveys suggest that most people drink tea or other hot beverages at temperatures below 65 degrees C.

“Those of us who drink hot beverages often should be prudent and wait for the liquid to cool a bit first,” Farin Kamangar and Neel Friedman, two public health researchers in US academic institutions, wrote in a commentary in the same issue of the journal. “However, the results of this study should not cause people to abandon their favourite beverages. Most people drink their tea and coffee at a temperature that seems unlikely to cause cancer,” they wrote.